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Manual Reference Pages  -  FORM::SENSIBLE::FAQ (3)

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Form::Sensible::FAQ - Answers to questions about how to use Form::Sensible



I have a hash that contains the field values, what’s the best way to get those into a Form::Sensible form? There are two ways to do this. The preferred way is usually to delegate your form’s field values to your hash. You often want to do this to link a form’s fields to a single source of data, for example, Catalyst’s $c->req->params hashref. This can be done easily using the Form::Sensible::Form’s delegate_all_field_values_to_hashref routine:


After that, all fields will get and set their values via the $c->req->params hashref.

<B>NOTE that this is actually a very bad idea if your forms are persistent from one request to the next, as the B>$c->req->params<B> from the initial request will be captured within a closure. If you are using persistent forms, you must re-set the delegate during each request or use an intermediate object instead that can obtain the current request’s parameters.B>

If you have not delegated your field’s values to something else (as indicated above), the form itself will store the values. In this case, you must push the values into the form object instead. You can accomplish this by calling $form->set_values($your_hashref);

How do I disable a field? Simply set the field’s ’editable’ attribute to false. Form::Sensible will ensure that the field is not editable by the end user. Note that when a field is disabled in HTML, the browser does NOT send the value when the form is submitted. Form::Sensible’s HTML renderer takes this into account and if a value exists on a field that is marked as not editable, a hidden field will be added to transport the value back to the form processor.
Can I set the options for my Select field directly from a DBIx::Class resultset? Yes. This is actually quite easy. You define an options_delegate on the Select field and use a subroutine similar to the following:

 ## defined as a named subroutine so that it can be reused as often as needed.
 sub get_options_from_rs {
     my $caller = shift;
     my $option_details = shift;

     return [
               map {
                    name => $_->get_column($option_details->{name_column}),
                    value => $_->get_column($option_details->{value_column})
                  } $option_details->{rs}->all()

Then set the options_delegate to use that function and pass the appropriate information:

 $field->options_delegate( FSConnector( \&get_options_from_rs,
        rs => $your_resultset->search({ ... }),
        name_column => name,
        value_column => id,

The FSConnector will pass your option_details hash to the get_options_from_rs function, and your options will be pulled from the database when they are needed (whether for validation or for display).


How do I create validation that involves multiple fields (like password and confirmation fields)? Individual field based validation is handled via the individual field’s validation hash. If you want to check multiple fields together you need to do whole-form level validation. This can be accomplished easily via the form’s validation hash as follows:

                        code => sub {
                                my ($form, $result) = @_;
                                if ($form->field(password)->value() ne $form->field(password2)->value()) {
                                    $result->add_error(password2, Passwords do not match);

HTML Rendering

    CSS tagging

How do I style forms created by Form::Sensible’s HTML renderer? Each element created by Form::Sensible’s HTML renderer is thoroughly marked up for CSS styling. Each element has a CSS ID and one or more classes. While the best way to decipher these is to simply generate a form and look at the IDs and classes on each element, we will endeavor to give you somewhat of a road map here.

First, all CSS ids and classes are prefixed. This prefix is ’fs_’ by default. It can be overridden by passing a css_prefix attribute in the default_options passed to the HTML renderer’s new() method. For the remainder of this explanation, we will assume that the default prefix of ’fs_’ is in use. The name of the form is also used in most IDs and classes. For the remainder of this explanation, we will use ’login’ as our form name.

First, each form is contained within a div. The div has an id of ’fs_’ + the name of the form + ’form_div’. So, for our ’login’ form, the ID of the div would be ’fs_login_form_div’. The containing div will also have two classes applied to it: ’fs_form_container’ and ’fs_login_form_container

The form element itself has an ID of ’fs_’ + form name + ’_form’ and again has two classes applied to it: ’fs_form’ and ’fs_login_form

A complete example of the form start from above would be:

    <div id="fs_login_form_div" class="fs_form_container fs_login_form_container">
        <form action="/formtest/submit" method="post" id="fs_login_form" class="fs_form fs_login_form" accept-charset="utf-8" enctype="multipart/form-data">

Each field in the form has a CSS id and several classes. For fields, the form name, the field’s name, and type are taken into account. Because there are so many classes and elements involved, we will simply provide an example based on the rendering of a text field called ’username’ in the ’login’ form.

    <div id="fs_username_div" class="fs_formfieldline fs_text fs_username">
        <label class="fs_label fs_text_label " for="fs_test_username_input">Username</label>
        <input type="text" id="fs_login_username_input" class="fs_input fs_text_input fs_username_input " name="username" />

Note that for the default template scheme the div that includes the field and its label always has a class of ’fs_formfieldline’ in addition to classes based on the field’s type and field name.

Certain field types have more complex rendering and therefore have more complex CSS id and class mappings (e.g., Select fields). The best way to understand these is to simply look at the results of rendering them.

One last thing to note is that when a field is disabled by setting the ’editable’ flag on the field to false, an additional class of ’noteditable’ will be added to the input element.

    HTML changes

How do I tell Form::Sensible about my own custom templates? Form::Sensible is built to allow you to easily switch themes or override individual fields or field types. In order to override the builtin templates, you must tell the renderer where your templates are. You do this by passing an ’additional_include_paths’ parameter to the HTML renderer constructor:

   my $html_renderer = Form::Sensible::Renderer::HTML->new({ additional_include_paths => [ /path/to/your/templates ] });
   #### OR #####
   my $html_renderer = Form::Sensible->get_renderer(HTML, { additional_include_paths => [ /path/to/your/templates ] });

Once you have done this, Form::Sensible will look in the directory or directories provided first for its templates, falling back to the pre-installed templates when a particular template is not found.

How do I override a field’s template or change the field wrapper? When rendering in HTML, for a given field the form name, field name and field type are all taken into account when searching for overrides. Let’s assume you have a Form called ’login_form’ and a ’username’ text field. Form::Sensible’s HTML renderer looks for templates (in its include_paths) in the following order and the first one found will be used:


This allows you to customize any field on any form by name or by type. Further, you only need to define the template for the items you wish to override. Anything not found here will fall through to the default templates that ships with Form::Sensible.

I don’t like the way labels for my fields are rendered, Can I change that? Yes. Use the methods described above to tell the HTML renderer where to look for your additional templates. Then simply create a ’’ template file. This is a standard Template::Toolkit wrapper file. You will have access to all the field information about the field as field and the rendered input element will be placed wherever you put the string [% content %].
I would like to change or add information to the start or end of my form, how do I do that? Use the methods described above and provide one of the following templates (assuming your form is called ’login_form’):

    ## for form start
    ## for form messages (errors and status)
    ## for form_end:

Note again that this allows you to change form start, messaging or ending on a per-form basis or globally for all forms.


See Form::Sensible::Delegation.

Miscelleneous Questions

How do I localize field names and error messages? Localization of forms can be accomplished through the use of delegates. Both the Form::Sensible::Validator class and Form::Sensible::Renderer::HTML::RenderedForm support localizing through delegates.

By providing a DelegateConnection|Form::Sensible::DelegateConnection to Form::Sensible::Validator’s message_delegate you can translate the error or status messages as necessary.

You can translate field names in the form in the same way by providing a DelegateConnection|Form::Sensible::DelegateConnection to Form::Sensible::Renderer::HTML::RenderedForm’s display_name_delegate

I’m using Catalyst and I would like my form objects to be persistent from one request to the next, how do I do that? <B>BEWARE: Here lie Monsters and really freaky problemsB>

Generally speaking, it is a bad idea to persist forms from one request to the next within Catalyst. The main reason is that you can not reliably delegate in many cases because many of Catalyst’s objects (such as Models and Controllers) can be created and destroyed within the request lifecycle in certain scenarios. This can be very difficult to predict and is prone to accidental breakage and bleed over.

If you feel you must try to do this, you have two options:
1. Ensure that none of your delegation is tied to Controllers or Models (or any other Component) that might use the context $c to do its job.
2. Create and persist ’skeleton forms’ that contain no delegation information, clone them per request and initialize the delegate connections on the newly created clone form.

If you do not take care to use one of these approaches, you are going to experience problems ranging from weird data consistency problems to full scale bleed over of form data between users. Considering the problems inherent to doing this, how to accomplish it is left as an exercise to the reader.

<B>NOTE:B> Persisting the basic form definition hash (as passed to Form::Sensible’s create_form routine) is not similarly problematic, though care should be taken to ensure that you don’t accidentally capture $c when creating your delegates. If, after reading the above you still want to know how to do this properly, drop by the #form-sensible irc channel on and we may be able to help.

Where can I go for help using Form::Sensible You can join the google discussion group:


OR look at the wiki:


OR drop by the irc channel: Join #form-sensible via your web browser <">>


Jay Kuri,


Ionzero LLC. <>


Copyright (c) 2010 the aforementioned authors. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
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